In the past few years, there has been a marked increase in the use of hollow metal doors in the building construction industry, compared to the use of traditional wooden doors. Also, as property owners become increasingly interested in security, the use of key-latch dead bolt locks in addition to regular door latches has also been on the increase. The task of installing a dead bolt lock in a hollow metal door has previously been a time consuming project, primarily due to the effort required to create a mortise in the edge of the door.
The mortise is an indented or offset portion on the edge of a door where a face plate is installed adjacent a bolt latch device. The bolt portion of the dead bolt assembly passes thorugh an aperture in the center of the face plate. The face plate must be installed so that its outer surface is flush with the edge of the door, whereby the door can open and close without interfering with the door jamb. The purpose of the mortise is to provide an indented or offset portion on the edge of the door for locating and receiving the dead bolt face plate.
One present state-of-the-art method of creating a mortise in a hollow metal door consists of cutting a square aperture in the door edge and using a metal bridge or wooden block to span the aperture. The dead bolt is then fastened on the bridge or block in the edge of the door. However, this solution has not produced professional-looking workmanship. The square aperture must be hewn out with a chisel, which leaves rough, unfinished edges around the aperture. In addition, a square hole in the door edge weakens the structural integrity of the door. Also, use of a chisel, saw and metal cutting wheel to cut the square aparture in the edge of the door is very time consuming, and increases the cost of installing dead bolt latches in hollow steel doors.
Other than the chisel-bridge system mentioned above for forming a mortise in a hollow metal door, the prior art is void of any easy-to-operate mechanism or tool which will easily and quickly produce a professional looking mortise. The relevant prior art consists of metal bending and joggling systems which form offsets in sheet metal structures, but there is no teaching of applying such systems to form mortises in hollow metal doors. Examples of such metal forming systems are found in U.S. Pat. Nos. 2,292,446; 2,363,931; and 3,289,454. U.S. Pat. No. 2,292,446 discloses a hand operated tool for dimpling and riveting sheet metal covers to airplanes, and does not disclose how a mortise could be applied to a hollow metal door. U.S. Pat. Nos. 2,363,931 and 3,289,454 disclose joggling tools for placing an offset in a sheet metal article. Neither of these patents disclose a device for creating a mortise in the edge of a hollow metal door.
As will be described in greater detail hereinafter, the present invention is adapted to allow a locksmith, or any other craftsman, to easily create a mortise in a hollow metal door to facilitate installation of a dead bolt latch.